Thermal cut-out.



No. 854,728. PATENTED MAY 28, 1907, J. T. H. DEMPSTER.

THERMAL GUT-OUT.

APPLICATION FILED NOV. 7, 1904.

\A/Itness es.

, Inventor: H 545 JohnTHDempster. 3% C 4 W Atty.

UNITED s'rA'rEs PATENT orrron.

JOHN T. H. DEMPSTER, OF SCHENEOTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

THERMAL CUT-OUT.

Patented May 28, 1907.

Application filed November 7, 1904:. Serial No. 231,662.

To all whom it may concern.-

Be it known that .I, J OHN T. H. DEMPSTER, a citizen ofthe Unitet States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Thermal Cut-Outs, of which the following is a specification.

The presentinvention relates to cut-out devices for interrupting electric circuits upon the passage therethrough of abnormal or dangerous currents, and more particularly to that class of such devices known as inclosed fuses, and characterized by the inclosure of.

the fusible element in a shell or casing which serves to prevent the danger due to the. gases of fusion and particles'of molten metal being expelled into contact with inflammable material.

The object of my invention is to rovide an electric fuse which will effectua ly and positively interrupt electric circuits carrying currents of large volume.

In carrying out my invention I employ a casing with the fusible element extending therethrough in the usual manner and surround the latter with a series of plates of heat conducting material with spaces between them so that when the fuse blows the gases of fusion will be expelled into intimate contact therewith and quickly condensed. By making the plates of magnetic material the magnetic induction is rendered useful in retarding the rise in potential through the fusible strip upon the o'ccu'rrenoe of a short circuit and thereby reduces the violence of the explosion due to the sudden transformation of the fusible element into gas.

For a more complete understanding of the invention reference may be had to the following detailed descriptionand the accompanying drawing forming a part of this specification, in which Figure 1 is a side elevation with part broken away of an inclosed fuse showing one form of my invention; and Fig: 2 is a cross section thereof. I

The casing consists of a tube '1 of stout insulating fiber closed at its ends by metallic caps 2 which are secured thereto by screws 3 having apertures in their ends in which con tact blades 4 are secured by outwardly-bent lugs 5 and pins 6 on opposite sides of the metal of the ends. The fusible strip 7 is con nected in the usual manner to contact blades 4.

, The base of the tube 1 has arranged throughout its. length a series of iron plates or washers 8 having central apertures 9 of a size to permit the fuse strip 7 and any insulation thereon to pass freely therethrough, and

these plates are heldspaced in planes transverse to the axis of the tube by insulating rings 10 fitting the bore of the tube.

When a short circuit is thrown upon a fuse constructed as above described the iron plates act inductively as a break to prevent the sudden rush of cur-rent through the fuse strip, and upon the volatilization of the strip 7-they quickly absorb the heat of the gases and deprive the are which forms upon the destruction of the fuse strip of its supporting medium, moreover, the arc in its passage through the. apertures of the plates 8 comes in contact with more or less of the exposed metal edges and subdivides itself into a plurality of small arcs which on account of their counter-electromotive forces efiectually cooperate to subdue the arcing action.

I do not desire to restrict myself to the particular form or arrangement of parts herein described and shown; since it is apparent that they may be changed and modified without departing from my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. An electric fuse comprising a fusible strip, and one or more independently insulated metal pieces surrounding said strip and adapted to condense the gases of fusion.

' 2. An electric fuse comprisin a fusible strip, and one or more meta mediums throu h which said strip is threaded.

3. in electric fuse comprising a casing, a fusible strip supported therein, and one or more pieces of metal having extended surfaces arranged in said casing.

4. An electric fuse comprising a casing, a fusible strip supported therein, and a series of metallwashers surrounding said strip within the casing.

5. An electric fuse comprising a casing, 21

thereof, and a series of iron Washers surrounding said strip.

7. An electric fuse comprising a tubular casing, a fusible strip supported axially 10 thereof, a series of metal Washers'arranged transversely in said casing and through which said fusible strip is threaded, and insu lating rings separatin said Washers.

In Witness whereof, have hereunto set my hand this 4th day of November, 1904.

JOHN T. H. DEMPSTER.

Witnesses:

BENJAMIN B. HULL, HELEN ORFoRD. 

